eardrum

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Eardrum
Anatomy of the human ear.
Right tympanic membrane as seen through a speculum.
Latin	membrana tympani
Gray's	subject #230 1039
MeSH	Tympanic+Membrane+Lydia
Dorlands/Elsevier	Tympanic membrane

The eardrum, or tympanic membrane, is a thin, cone-shaped membrane that separates the external ear from the middle ear in humans and other tetrapods. Its function is to transmit sound from the air to the ossicles inside the middle ear. The malleus bone bridges the gap between the eardrum and the other ossicles.

The are two general regions of the tympanic membrane: the pars flaccida (upper region, see picture on right) and the pars densa. The pars flaccida consists of two layers, is relatively fragile, and is associated with eustachian tube dysfunction and cholesteatomas. The larger pars densa region consists of three layers (ectoderm, entoderm, and mesoderm), is comparatively robust, and is the region most commonly associated with perforations.

Rupture or perforation of the eardrum can lead to conductive hearing loss. Collapse or retraction of the ear drum can also cause conductive hearing loss or even cholesteatoma.

Intentional rupture

The Bajau people of the Pacific intentionally rupture their eardrums at an early age in order to facilitate diving and hunting at sea. Many older Bajau therefore have difficulties hearing.^[1]

Gallery

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  External and middle ear, opened from the front. Right side.

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  Horizontal section through left ear; upper half of section.

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  The right membrana tympani with the hammer and the chorda tympani, viewed from within, from behind, and from above.

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  Auditory tube, laid open by a cut in its long axis.

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  Chain of ossicles and their ligaments, seen from the front in a vertical, transverse section of the tympanum.

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  Right tympanic membrane as seen through a speculum.

References

External links

Wikimedia Commons has media related to: Eardrum

• Diagram at Georgia State University
• drtbalu's otolaryngology online